My advice, don't use one. The mist feels good for about 15seconds, then you just feel clammy. Unless we are getting all wet, like swimming- we feel far better if we just stay dry on the outside.
On the other hand, we make sure to stay plenty wet on the inside. Instead of a mister, we make sure to drink plenty of water.
The other investment I advise is to acclimate yourself to the heat as much as possible before you go. Go outdoors, avoid AC as much as possible. Set your home thermostat as high as possible. the more you acclimate yourself to the heat, the less it will bother you.